Goof: Willow claims the book from which the mark of Gachnar was taken is written in Gaelic, however, when the book is shown to Buffy (both in the frat house and at Giles'), the writing in it is in plain English (describing exorcisms).
We learn in this episode that Anya is afraid of bunnies, a humorous and recurring theme for her character.
Anya tells Xander that his uncle, Rory, let her in his house and that he smelled like peppermint. Xander replies "the man likes his Schnapps". In the season three episode "The Zeppo", Xander mentions that Uncle Rory is an alcoholic, and in season six we get to see him briefly.
Goof: When Anya goes to Giles' apartment dressed as a bunny, she takes the "paws" off of her hands. She isn't wearing them when Giles cuts a hole in the house with the chainsaw, but they are back on her hands when she hugs Xander after she and Giles find the gang.
Giles: (reading from the book) There are two ways in here to get rid of Gachnar. Destroying the symbol... (Buffy walks past him and punches into the floor, destroying the sigil on the floor and tearing up the boards, she stands up with an accomplished look on her face) ...is not one of them and will immediately conjure the fear demon itself!
Xander (observing Anya's costume): So... this is your scary costume?
Anya (defensively) Bunnies frighten me.
Buffy: Like the tux, Xander!
Xander: Bond. James Bond. Insurance, you know, in case we get turned into our costumes again. I'm going for cool, secret agent guy.
Buffy: I hate to break it to you, but you'll probably end up cool head waiter guy.
Xander: As long as I'm cool and wield some sort of power.
Anya: Well first there was no door where the door should be, and then I saw a girl in a window and then she was gone!
Giles: She disappeared from the window?
Anya: No, the window disappeared from the house.
Buffy: Thank the Lord.
Oz: You're welcome.
Buffy: This is Gachnar?
Xander: Big overture. Little show.
Gachnar: I am the dark lord of nightmares. The bringer of terror! Tremble before me. Fear me!
Willow: He... he's so cute!
Xander: Who's the little fear demon? Come on, who's the little fear demon?
Giles: Don't taunt the fear demon.
Xander: Why, can he hurt me?
Giles: No. It's just... tacky.
Buffy: Perfect. Everybody's got a date but third-wheel Buffy.
Willow: You're not a third wheel.
Xander: Well, technically speaking, you're a fifth wheel.
Xander: What ya got in the basket, little girl?
Willow: We have to make sure she has fun. We have to force fun upon her. Yeah, and if Parker shows up, we'll just axe-murder him. That's Halloweeny.
Xander: I can't say seeing you falls into the realm of a bad thing.
Anya: Really? I thought maybe we could go out tonight. For our anniversary.
Anya: It's been exactly one week since we copulated.
Willow: I'll know when I've reached my limit.
Oz: Wine coolers?
Oz: Ooh. Didn't encourage her, did you?
Willow: Where's supportive boyfriend guy?
Oz: Oh, he's picking up your dry-cleaning. But he told me to tell you he's afraid you're gonna get hurt.
Willow: Okay, Brutus. Brutus. Uh, Caesar? Betrayal, trusted friend, back-stabby?
Xander: People, prepare to have your spines tingled and your gooses bumped by the terrifying... Fantasia. Fantasia?
Oz: Maybe it's because of all the horrific things we've seen, but hippos wearing tutus just don't unnerve me the way they used to.
Xander: I don't know - I was going for ferocious scary, but it's coming out more dryly sardonic.
Willow: It does appear to be mocking you with its eyeholes.
Oz: Yet its nosehole seems sad and full of self-loathing.
Buffy: I was just thinking about the life of a pumpkin. Grow up in the sun, happily entwined with others, and then someone comes along, cuts you open, and rips your guts out.
Buffy: Let's be realistic Willow, your basic spells are usually only about 50/50.
Willow: Oh yeah? Well, so's your face!
Giles: Bloody hell, the inscription!
Giles: I should've translated the Gaelic inscription beneath the picture.
Buffy: What does it say?
Giles: Actual size.
Buffy: This is much better. There is no problem that cannot be solved with chocolate.
Willow: I think I'm gonna barf.
Buffy: 'Cept that.
Willow: I'm Joan of Arc, well I figure we had a lot in common. Seeing as how I was almost burned at the stake, and she had that close relationship with God.
Xander: (to Oz) And what are you supposed to be?
(Oz opens his jacket and reveals a name tag that says "Hi my name is God")
Giles' Mexican costume and Anya's bunny suit were so popular with fans that special variant editions of their action figures were made with these outfits. These quickly became two of the most popular figures in the entire line, and the "Bunny Anya" was even reissued years later.
Students are preparing the party -- "Kool" by 28 Days
People arrive at the party -- "Ow Ow Ow" by Third Grade Teacher
The Scooby Gang arrives at the party -- "Pretty Please" by Verbena
Buffy is dressed as Little Red Riding Hood. When Xander asks what is in her basket, she replies, "Weapons." There is a character in a series of Japanese fighting video games dressed as Red Riding Hood who carries a basket full of weapons. Whether or not this was an intentional reference is unknown.
This is the first episode David Fury writes as an official Mutant Enemy writer. His scripts in seasons two and three were freelance work since he initially turned down a Buffy writing job in 1997 (season one).
Oz: She's still suffering a little post-Parker depression.
This is a play on "post-partum depression", a common—and sometimes very serious—problem among women shortly after giving birth.
Xander: What'cha got in the basket, little girl?
This is a reference to Buffy's Little Red Riding Hood costume. In some versions of the Little Read Riding Hood fairy tale she meets a wolf in the woods on her way to her grandmothers house and he'll often ask her what she has in her basket. When she gets to her grandmothers house, the wolf has locked her grandmother in the closet (or eaten her, depending on the story version) and dressed up in her clothes to trick Red Riding Hood in an attempt to eat her.
Xander: The man likes his schnapps.
Schnapps is a generic name for a flavorful, usually clear alcoholic beverage made from fermented grain and flavored with various herbs or fruits. Schnapps can come in a variety of flavors including strawberry, peppermint, orange, butterscotch, and many others.
Buffy: If I were Abbott and Costello this would be fairly traumatic.
This is a reference to the comedy duo of Bud Abbott and Lou Costello that had a show together and made several movies in the 1940's and 50's. In many of their movies Abbott and Costello would meet various monsters such as: Frankenstein, The Mummy, and Dr. Jekyll and Mr. Hyde.
Willow (about the camouflaged guys): What are they supposed to be?
NATO is the North Atlantic Treaty Organization, a military alliance established in 1949. Its aim was to safeguard member nations from attack with the end of the Cold War, NATO has increasingly concentrated on extending security and stability throughout Europe, and on peacekeeping efforts in Europe and elsewhere.
Willow: I'm Joan of Arc. I figured we had a lot in common, being almost burned at the stake and having a close relationship with God.
Joan of Arc is a patron saint of France and hero of the Hundred Years War. As a teenager she believed that God spoke to her and urged her to save France from English domination. She lead an army that attacked the English and forced them to retreat from Orleans. The English eventually captured her, tried her for heresy and sorcery, and burned her at the stake. In 1920, she was canonized (made a saint) by the Catholic Church.
Giles: It's alive.
As Giles hits the small hanging Frankenstein's monster figure, he says "It's alive." This is an homage to the scene from the classic 1931 film, Frankenstein, in which the Dr. Frankenstein says the same thing when his newly animated monster begins to move.
Willow / Music soundtrack: As Willow begins her attempted will-o-the-wisp spell, the background music quietly changes to the beginning strains of Dukas's "Sorcerer's Apprentice" (or something very much like it). When the will-o-the-wisp first splits in two, the rising strings o' peril from the piece come in just as they would for Mickey's brooms splitting exponentially out of control. This also disproves the earlier notion that Fantasia can't be scary.
Xander: Prepare to have your spines tingled, your gooses bumped by the terrifying ... Fantasia.
Oz: Maybe it's all the terrifying things we've seen, but hippos wearing tutus just don't unnerve me the way they used to.
Fantasia is a Disney movie from 1940 that consists of animated scenes backed by a classical music score. The most famous sequence is probably Mickey Mouse as the sorcerer's apprentice. The movie also contains a scene with hippos in tutus dancing.
Xander: Sensing a disturbance in the force, master?
Reference to the Force, the energy field which binds together all living things, which is featured in the Star Wars series of fantasy/sci-fi films.
Title: Fear, Itself
The title is part of the famous speech given by President Franklin Roosevelt during World War II: "We have nothing to fear but fear, itself."
Xander: Bond. James Bond.
Xander goes dressed as the famous British spy of book and movie James Bond. This is the classic catch phrase of the series.
Oz: Mi casio es su casio.
Oz makes a play on the Spanish phrase "Mi casa es su casa" (My home is your home) along with Casio a brand of electronic equipment.
Frat guy #1: Is there any holiday that's not about getting laid?
Frat guy #2: Arbor Day.
Arbor Day is a little celebrated holiday on the last Friday in April that is supposed to be about planting trees.
Willow: Okay, Brutus. ... Brutus? ... Caesar? ... Betrayal ... trusted friend? ... Back stabby?
Willow explains her own historical reference to Brutus (Marcus Junius Brutus) who was a leader of the conspirators who killed Julius Caesar.
Xander: Phantasm. It was supposed to be Phantasm. Stupid video store.
Phantasm is a horror/sci-fi movie from 1979 that carried the tagline "If this one doesn't scare you, you're already dead".